Various compositions are known to be useful as treating agents to provide surface effects to substrates. Surface effects include repellency to moisture, soil, and stains, and other effects, which are particularly useful for fibrous substrates and other substrates such as hard surfaces. Many such treating agents are fluorinated polymers or copolymers.
Most commercially available fluorinated polymers useful as treating agents for imparting repellency to substrates contain predominately eight or more carbons in the perfluoroalkyl chain to provide the desired repellency properties. Honda et al, in Macromolecules, 2005, 38, 5699-5705 disclose that for perfluoroalkyl chains of greater than 8 carbons, orientation of the Rf groups is maintained in a semi-crystalline configuration while for such chains having less than 6 carbon atoms, reorientation occurs.
Various attempts have been made to improve particular surface effects and to increase the fluorine efficiency; i.e., boost the efficiency or performance of treating agents so that lesser amounts of the expensive fluorinated polymer are required to achieve the same level of performance or have better performance using the same level of fluorine. It is desirable to reduce the chain length of the perfluoroalkyl groups thereby reducing the amount of fluorine present, while still achieving the same or superior surface effects. Use of shorter chain perfluoroalkyl groups is one way to reduce the amount of fluorine present. Other approaches provide alternative mechanisms for structure and ordering in the fluorinated materials having short fluorinated tails. For instance, one approach is to combine the characteristics of structures known to undergo gelation via, for instance, hydrogen bonding, with short perfluorinated alkyl moieties. The ordering imposed upon the perfluorinated alkyl groups by the hydrogen bonding networks may amplify the ability of the perfluorinated alkyl moieties to order, thus increasing the fluorine efficiency of surface treating agents comprising such structures.
There is a continuing need for compositions that improve the repellency and stain resistance of treating agents for fibrous and/or porous substrates and hard surface substrates while using lower levels of fluorine. The present invention is directed to these, and other, important ends.